Preparation method of iron-manganese prussian blue and application thereof in aqueous zinc battery

Abstract

The application relates to a preparation method of iron-manganese prussian blue and application thereof to aqueous zinc batteries, and belongs to the technical field of preparation of positive electrode materials of metal ion batteries. The preparation method is based on a coprecipitation method. Potassium ferrocyanide is mixed with ferrous salt, manganese salt and a complexing agent, and then subjected to aging, centrifugal separation and washing to obtain an iron-manganese prussian blue material. Benefited from the synergistic effect of Fe / Mn and the regulation effect of the complexing agent on the iron-manganese prussian blue material, the finally obtained material presents irregular particles and exhibits good aqueous zinc battery performance. The material exhibits an ultra-high specific capacity of 135 mAh g ‑1 -1 at a current density of 0.5 A g ‑1 -1, and simultaneously has good cycle stability. The preparation method of the positive electrode material is simple, low in cost and good in stability, and lays a foundation for large-scale preparation of positive electrode materials of aqueous zinc batteries.

Description

Technical Field

[0001] This invention belongs to the technical field of metal-ion battery cathode material preparation, specifically relating to a method for preparing iron-manganese Prussian blue and its application in aqueous zinc batteries. Background Technology

[0002] Lithium-ion batteries have dominated the energy storage field for decades, but the scarcity of lithium resources, toxic electrolytes, and safety issues have severely hindered their further large-scale energy storage applications. Aqueous zinc batteries, due to their low cost and high safety, have shown great application potential in recent years. Zinc metal has advantages such as abundant reserves, low cost, environmental friendliness, low redox potential, and high reversibility. In aqueous electrolytes, it is not only safer but also significantly reduces battery assembly costs. By drawing inspiration from lithium-ion batteries, aqueous zinc batteries have made rapid progress in cathode materials, such as manganese oxides, vanadium oxides, and Prussian blue analogs. While Prussian blue analogs possess high operating voltage, high rate performance, and high energy density, their crystal defects limit their further development. Because they are synthesized in aqueous solutions, they readily generate Fe(CN)6 vacancies, which are occupied by water molecules, ultimately resulting in a large amount of adsorbed and bound water in the material. During charge and discharge, the high water concentration causes structural distortion or even collapse of the material, leading to decreased electrochemical stability. Meanwhile, Fe(CN)6 is the capacity-contributing site for the redox reaction during the charge-discharge process of Prussian blue analogues. High concentration defects lead to the absence of reaction sites in the reactants, with only a portion of Fe participating in redox reactions, resulting in a decrease in specific capacity. The prepared Prussian blue material exhibits a low specific capacity (<70 mAh g). -1 The bottleneck problem. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, this invention aims to provide a low-cost, scalable method for preparing Prussian blue cathode materials with low water content, low defects, and high crystallinity, and its application in aqueous zinc batteries. To achieve the above-mentioned objective and solve the problems existing in the prior art, the technical solution of this invention is as follows: This invention provides a method for preparing iron-manganese Prussian blue, comprising the following steps:

[0004] (1) Solution preparation: Dissolve K4Fe(CN)6·3H2O in deionized water to obtain solution A, and dissolve FeSO4·7H2O, MnSO4·H2O and the complexing agent in deionized water to obtain solution B;

[0005] The concentration of K4Fe(CN)6 in solution A is 0.02 mol / L. -1 ~0.06 mol L -1 The concentration of FeSO4 in solution B is 0.008 mol / L.-1 ~0.04 mol L -1 The concentration of MnSO4 is 0.02 mol / L. -1 ~0.04 mol L -1 The concentration of the ligand is 0.008 mol L. -1 ~0.3 mol L -1 .

[0006] (2) Coprecipitation synthesis: Solution B is added to solution A at a certain rate, stirred and mixed, aged, and the precipitate is separated by centrifugation, washed with ethanol and deionized water, and dried in a vacuum oven at 70-90℃ to obtain iron-manganese Prussian blue cathode material.

[0007] In step (1), the ligand is selected from either dipotassium ethylenediaminetetraacetate or tripotassium citrate. In step (2), solution B is added at a rate of 6 mL / min. -1 ~12mL min -1 .

[0008] The reaction temperature in step (2) is 5℃~60℃.

[0009] The iron-manganese Prussian blue cathode material is used in aqueous zinc batteries.

[0010] Further preparation methods include the following steps:

[0011] (1) Solution preparation: Dissolve 1 mmol to 3 mmol K4Fe(CN)6·3H2O in 50 mL of deionized water to obtain solution A, and dissolve 0.4 mmol to 2 mmol FeSO4·7H2O, 1 mmol to 2 mmol MnSO4·H2O and 0.4 mmol to 10 mmol complexing agent in 50 mL of deionized water to obtain solution B;

[0012] (2) Coprecipitation synthesis: Solution B was diluted with 6 mL / min -1 ~12mL min -1 Solution A was added, and the mixture was stirred and mixed at 5℃~60℃. After aging for 24 hours, the precipitate was separated by centrifugation and washed with ethanol and deionized water. The precipitate was then dried in a vacuum drying oven at 80℃ for 15 hours to obtain the iron-manganese Prussian blue cathode material.

[0013] As a preferred technical solution of the present invention, in the preparation method of the iron-manganese Prussian blue material for the positive electrode of an aqueous zinc battery:

[0014] Furthermore, in step (1), the ligand is selected from either dipotassium ethylenediaminetetraacetate or tripotassium citrate.

[0015] The amounts of ethylenediaminetetraacetic acid dipotassium salt in step (1) were 2.5 mmol, 1.7 mmol, 1.2 mmol, 0.7 mmol, and 0.4 mmol, respectively.

[0016] In step (2), the addition rate of solution B is 6 mL / min. -1 9mL min -1 12mL min -1 .

[0017] The synthesis temperatures in step (2) are 5℃, 25℃, and 60℃.

[0018] The present invention also provides a full cell prepared using the above-mentioned iron-manganese Prussian blue material, which includes the following steps:

[0019] Positive electrode preparation: 70 mg of Prussian blue iron-manganese positive electrode material, 20 mg of acetylene black, and 10 mg of polyvinylidene fluoride were ground in a mortar for 20 min. A few drops of N-methylpyrrolidone were added, and the mixture was ground for another 5 min to obtain a slurry. The slurry was uniformly coated on the surface of the current collector and vacuum dried at 60 °C for 3 h to obtain a loading of 1-3 mg cm⁻¹. -2 The positive electrode plate.

[0020] Assembly: At room temperature, the positive electrode shell, positive electrode sheet (iron-manganese Prussian blue), separator, electrolyte, negative electrode sheet (zinc sheet), gasket, spring sheet, and negative electrode shell are stacked in sequence and sealed with a sealing machine. An aqueous solution containing zinc trifluoromethanesulfonate is used as the electrolyte to complete the battery assembly.

[0021] Testing: The battery testing system is the Blue Electric testing system, and the testing voltage window is 0.1-2.05V.

[0022] The advantages of this invention are:

[0023] 1. Adding Mn ions to iron-based Prussian blue materials allows them to work synergistically with Fe ions to form Fe / Mn coexisting Prussian blue materials. Through the synergistic effect of FeN6, FeC6, and MnN6 octahedra in the coordination structure, the crystal structure is stabilized, the dissolution of active atoms during cycling is suppressed, and a longer cycle life is obtained.

[0024] 2. Compared with other processes, this process is synthesized at room temperature, and only a small amount of ligand is added to slow down the nucleation rate, which greatly reduces the synthesis cost and is conducive to industrialization. Attached Figure Description

[0025] Figure 1 The Prussian blue material for aqueous zinc battery cathodes prepared in Examples 1-3 is in a concentration of 0.5 A g. -1 The charge-discharge curves at current density illustrate the role of the iron-manganese composite Prussian blue material.

[0026] Figure 2 The aqueous zinc battery cathode iron-manganese Prussian blue material prepared in Examples 3-5 is in 0.5A g -1 The charge-discharge curves at current density illustrate the effect of the ligand on the iron-manganese Prussian blue material. In the figure, 1 represents the addition of dipotassium ethylenediaminetetraacetate (EDTA), 2 represents the addition of tripotassium citrate (TCC), and 3 represents the absence of any ligand.

[0027] Figure 3 The aqueous zinc battery cathode iron-manganese Prussian blue material prepared in Examples 6-10 is in 0.5A g -1 The charge-discharge curves at current density illustrate the optimal addition amount of dipotassium ethylenediaminetetraacetate.

[0028] Figure 4 The aqueous zinc battery cathode iron-manganese Prussian blue material prepared in Examples 8, 11-12 is in 0.5Ag -1 The charge-discharge curves at current density illustrate the optimal mixing rate.

[0029] Figure 5 The aqueous zinc battery cathode iron-manganese Prussian blue material prepared in Examples 8, 13-14 is in 0.5 Ag -1 The charge-discharge curves at current density illustrate the optimal reaction temperature.

[0030] Figure 6 This is a scanning electron microscope (SEM) image of the Prussian blue iron-manganese cathode material for an aqueous zinc battery prepared in Example 8.

[0031] Figure 7 The full cell assembled using the aqueous zinc battery cathode material, iron-manganese-Prussian blue, prepared in Example 8, has a 0.5 Ag content. -1 Cyclic performance test results at current density.

[0032] Figure 8 Comparative Example 1 shows the preparation of an aqueous zinc battery cathode material based on iron-based Prussian blue at a concentration of 0.5 A g. -1 Charge-discharge curves at current density.

[0033] Figure 9 Comparative Example 2 shows the preparation of a manganese-based Prussian blue cathode material for an aqueous zinc battery at 0.5 Ag. -1 Charge-discharge curves at current density.

[0034] Figure 10 Comparative Examples 1, 1, and 3 show the preparation of aqueous zinc battery cathode iron-based Prussian blue materials in 0.5 Ag. -1Charge-discharge curves at current density. In the figure, 1 represents iron-based Prussian blue material without a coordinating agent, 2 represents iron-based Prussian blue material with dipotassium ethylenediaminetetraacetate (EDTA) added as a coordinating agent, and 3 represents iron-manganese composite Prussian blue material.

[0035] Figure 11 Comparative Example 2 and Examples 2-3 show the manganese-based Prussian blue material for aqueous zinc battery cathodes prepared in 0.5 A g. -1 Charge-discharge curves at current density. In the figure, 1 represents manganese-based Prussian blue material without a coordinating agent, 2 represents manganese-based Prussian blue material with dipotassium ethylenediaminetetraacetate (EDTA) added as a coordinating agent, and 3 represents iron-manganese composite Prussian blue material. Detailed Implementation

[0036] The present invention will be further described below with reference to the embodiments.

[0037] Example 1

[0038] (1) Solution preparation: Dissolve 2 mmol K4Fe(CN)6·3H2O in 50 mL of deionized water to obtain solution A, and dissolve 2 mmol FeSO4·7H2O in 50 mL of deionized water to obtain solution B;

[0039] (2) Coprecipitation synthesis: Solution B was prepared by adding 9 mL of solution at a concentration of 100000 -1 Solution A was added, and the mixture was stirred at 25°C. After aging for 24 hours, the precipitate was centrifuged and washed with ethanol and deionized water. The precipitate was then dried in a vacuum oven at 80°C for 15 hours to obtain iron-based Prussian blue (FeHCF) cathode material.

[0040] Example 2

[0041] (1) Solution preparation: Dissolve 2 mmol K4Fe(CN)6·3H2O in 50 mL of deionized water to obtain solution A, and dissolve 2 mmol MnSO4·H2O in 50 mL of deionized water to obtain solution B;

[0042] (2) Coprecipitation synthesis: Solution B was prepared by adding 9 mL of solution at a concentration of 100000 -1 Solution A was added and stirred at 25°C. After aging for 24 hours, the precipitate was centrifuged and washed with ethanol and deionized water. The precipitate was then dried in a vacuum oven at 80°C for 15 hours to obtain manganese-based Prussian blue (MnHCF) cathode material.

[0043] Example 3

[0044] (1) Solution preparation: Dissolve 2 mmol K4Fe(CN)6·3H2O in 50 mL of deionized water to obtain solution A, and dissolve 0.7 mmol FeSO4·7H2O and 1.3 mmol MnSO4·H2O in 50 mL of deionized water to obtain solution B;

[0045] (2) Coprecipitation synthesis: Solution B was prepared by adding 9 mL of solution at a concentration of 100000 -1 Solution A was added, and the mixture was stirred and mixed at 25°C. After aging for 24 hours, the precipitate was centrifuged and washed with ethanol and deionized water. The precipitate was then dried in a vacuum oven at 80°C for 15 hours to obtain the iron-manganese Prussian blue (FeMnHCF) cathode material.

[0046] Please see Figure 1 The figure shows the Prussian blue material of the aqueous zinc battery cathode prepared in Examples 1-3 at 0.5 A g. -1 Charge-discharge curves at current densities. By comparing the electrochemical performance of the aqueous zinc battery cathode materials prepared in Examples 1-3—iron-based Prussian blue, manganese-based Prussian blue, and iron-manganese Prussian blue—Example 3 exhibited the highest electrochemical performance at 0.5 A g. -1 At a current density of 104 mAh g, its specific capacity can reach 104 mAh g. -1 Because Mn ions are added to iron-based Prussian blue materials, they work synergistically with Fe ions to form Fe / Mn coexisting Prussian blue materials. Through the synergistic effect of FeN6, FeC6, and MnN6 octahedra in the coordination structure, the crystal structure is stabilized, thereby improving service life and performance.

[0047] Example 4

[0048] (1) Solution preparation: Dissolve 2 mmol K4Fe(CN)6·3H2O in 50 mL of deionized water to obtain solution A, and dissolve 0.7 mmol FeSO4·7H2O, 1.3 mmol MnSO4·H2O and 10 mmol tripotassium citrate in 50 mL of deionized water to obtain solution B;

[0049] (2) Coprecipitation synthesis: Solution B was prepared by adding 9 mL of solution at a concentration of 100000 -1 Solution A was added, and the mixture was stirred and mixed at 25°C. After aging for 24 hours, the precipitate was centrifuged and washed with ethanol and deionized water. The precipitate was then dried in a vacuum oven at 80°C for 15 hours to obtain the iron-manganese Prussian blue cathode material.

[0050] Example 5

[0051] (1) Solution preparation: Dissolve 2 mmol K4Fe(CN)6·3H2O in 50 mL of deionized water to obtain solution A, and dissolve 0.7 mmol FeSO4·7H2O, 1.3 mmol MnSO4·H2O and 15 mmol of dipotassium ethylenediaminetetraacetate in 50 mL of deionized water to obtain solution B;

[0052] (2) Coprecipitation synthesis: Solution B was prepared by adding 9 mL of solution at a concentration of 100000 -1 Solution A was added, and the mixture was stirred and mixed at 25°C. After aging for 24 hours, the precipitate was centrifuged and washed with ethanol and deionized water. The precipitate was then dried in a vacuum oven at 80°C for 15 hours to obtain the iron-manganese Prussian blue cathode material.

[0053] Please see Figure 2 The figure shows the Prussian blue material of the aqueous zinc battery cathode prepared in Examples 3-5 at 0.5 A g. -1 Charge-discharge curves at current density. By comparing the aqueous zinc battery cathode iron-manganese Prussian blue materials prepared in Examples 3-5, it can be seen that the iron-manganese Prussian blue cathode material prepared under the conditions of Example 4 exhibits the best electrochemical performance at 0.5 A g. -1 At a current density of 133 mAh g, its specific capacity can reach 133 mAh g. -1 The addition of the ligand prevents transition metal ions from rapidly coordinating with ferricyanide, thus slowing down the nucleation and grain aggregation growth of Prussian blue. Example 4 showed a significant performance improvement due to the addition of a large amount of tripotassium citrate, while Example 5, due to the addition of an excessive amount of dipotassium ethylenediaminetetraacetate (EDTA), exhibited lower performance than Examples 3 and 4. Considering the synthesis cost, only a small amount of a strong ligand is needed to slow down the nucleation rate; therefore, EDTA was subsequently chosen as the ligand.

[0054] Example 6

[0055] (1) Solution preparation: Dissolve 2 mmol K4Fe(CN)6·3H2O in 50 mL of deionized water to obtain solution A, and dissolve 0.7 mmol FeSO4·7H2O, 1.3 mmol MnSO4·H2O and 2.5 mmol dipotassium ethylenediaminetetraacetate in 50 mL of deionized water to obtain solution B;

[0056] (2) Coprecipitation synthesis: Solution B was prepared by adding 9 mL of solution at a concentration of 100000 -1 Solution A was added, and the mixture was stirred and mixed at 25°C. After aging for 24 hours, the precipitate was centrifuged and washed with ethanol and deionized water. The precipitate was then dried in a vacuum oven at 80°C for 15 hours to obtain the iron-manganese Prussian blue cathode material.

[0057] Example 7

[0058] (1) Solution preparation: Dissolve 2 mmol K4Fe(CN)6·3H2O in 50 mL of deionized water to obtain solution A, and dissolve 0.7 mmol FeSO4·7H2O, 1.3 mmol MnSO4·H2O and 1.7 mmol dipotassium ethylenediaminetetraacetate in 50 mL of deionized water to obtain solution B;

[0059] (2) Coprecipitation synthesis: Solution B was prepared by adding 9 mL of solution at a concentration of 100000 -1 Solution A was added, and the mixture was stirred and mixed at 25°C. After aging for 24 hours, the precipitate was centrifuged and washed with ethanol and deionized water. The precipitate was then dried in a vacuum oven at 80°C for 15 hours to obtain the iron-manganese Prussian blue cathode material.

[0060] Example 8

[0061] (1) Solution preparation: Dissolve 2 mmol K4Fe(CN)6·3H2O in 50 mL of deionized water to obtain solution A, and dissolve 0.7 mmol FeSO4·7H2O, 1.3 mmol MnSO4·H2O and 1.2 mmol dipotassium ethylenediaminetetraacetate in 50 mL of deionized water to obtain solution B;

[0062] (2) Coprecipitation synthesis: Solution B was prepared by adding 9 mL of solution at a concentration of 100000 -1 Solution A was added, and the mixture was stirred and mixed at 25°C. After aging for 24 hours, the precipitate was centrifuged and washed with ethanol and deionized water. The precipitate was then dried in a vacuum oven at 80°C for 15 hours to obtain the iron-manganese Prussian blue cathode material.

[0063] Example 9

[0064] (1) Solution preparation: Dissolve 2 mmol K4Fe(CN)6·3H2O in 50 mL of deionized water to obtain solution A, and dissolve 0.7 mmol FeSO4·7H2O, 1.3 mmol MnSO4·H2O and 0.7 mmol dipotassium ethylenediaminetetraacetate in 50 mL of deionized water to obtain solution B;

[0065] (2) Coprecipitation synthesis: Solution B was prepared by adding 9 mL of solution at a concentration of 100000 -1 Solution A was added, and the mixture was stirred and mixed at 25°C. After aging for 24 hours, the precipitate was centrifuged and washed with ethanol and deionized water. The precipitate was then dried in a vacuum oven at 80°C for 15 hours to obtain the iron-manganese Prussian blue cathode material.

[0066] Example 10

[0067] (1) Solution preparation: Dissolve 2 mmol K4Fe(CN)6·3H2O in 50 mL of deionized water to obtain solution A, and dissolve 0.7 mmol FeSO4·7H2O, 1.3 mmol MnSO4·H2O and 0.4 mmol dipotassium ethylenediaminetetraacetate in 50 mL of deionized water to obtain solution B;

[0068] (2) Coprecipitation synthesis: Solution B was prepared by adding 9 mL of solution at a concentration of 100000 -1 Solution A was added, and the mixture was stirred and mixed at 25°C. After aging for 24 hours, the precipitate was centrifuged and washed with ethanol and deionized water. The precipitate was then dried in a vacuum oven at 80°C for 15 hours to obtain the iron-manganese Prussian blue cathode material.

[0069] Please see Figure 3 The figure shows the charge-discharge curves of the aqueous zinc battery cathode iron-manganese Prussian blue materials prepared in Examples 6-10. By comparing the electrochemical performance of the aqueous zinc battery cathode iron-manganese Prussian blue materials prepared in Examples 6-10, the electrochemical performance of Example 8 was the highest at 0.5 A g. -1 At a current density of 135 mAh g, its specific capacity can reach 135 mAh g. -1 .

[0070] Example 11

[0071] Based on Example 8, keeping other conditions unchanged, the addition rate in step (2) of Example 8 was changed to 6 mL / min. -1 Iron-manganese Prussian blue cathode material was obtained.

[0072] Example 12

[0073] Based on Example 8, keeping other conditions unchanged, the addition rate in step (2) of Example 8 was changed to 12 mL / min. -1 Iron-manganese Prussian blue cathode material was obtained.

[0074] Please see Figure 4 The figure shows the charge-discharge curves of the aqueous zinc battery cathode iron-manganese Prussian blue materials prepared in Examples 8, 11-12. By comparing the aqueous zinc battery cathode iron-manganese Prussian blue materials prepared in Examples 8, 11, and 12, it can be seen that the iron-manganese Prussian blue cathode material prepared under the conditions of Example 8 exhibits the best electrochemical performance at 0.5 A g. -1 At a current density of 135 mAh g, its specific capacity can reach 135 mAh g. -1 .

[0075] Example 13

[0076] Based on Example 8, keeping other conditions unchanged, the synthesis temperature in step (2) of Example 8 was changed to 5°C to obtain the iron-manganese Prussian blue cathode material.

[0077] Example 14

[0078] Based on Example 8, keeping other conditions unchanged, the synthesis temperature in step (2) of Example 8 was changed to 60°C to obtain the iron-manganese Prussian blue cathode material.

[0079] Please see Figure 5 The figure shows the charge-discharge curves of the aqueous zinc battery cathode iron-manganese Prussian blue material prepared in Examples 8, 13-14. By comparing the aqueous zinc battery cathode iron-manganese Prussian blue materials prepared in Examples 8, 13, and 14, it can be seen that the aqueous zinc battery cathode iron-manganese Prussian blue material prepared under the conditions of Example 8 has the best electrochemical performance.

[0080] Please see Figure 6 The figure shows the SEM morphology of the aqueous zinc battery cathode iron-manganese Prussian blue material prepared in this embodiment. As can be seen from the figure, after adding the coordinating agent dipotassium ethylenediaminetetraacetic acid, the zinc-ion battery cathode iron-manganese Prussian blue material exhibits many irregular particles.

[0081] Please see Figure 7 The figure shows the full cell assembled in this embodiment based on the aqueous zinc battery cathode material, iron-manganese Prussian blue, at 0.5 A g. -1 Cyclic performance test results at current density. As shown in the figure, at 0.5 Ag... -1 At current density, the capacity remains at 99 mAh g after 4000 cycles. -1 The coulomb efficiency is close to 100%, with a decay rate of 0.7% per revolution.

[0082] Comparative Example 1

[0083] Based on Example 1, keeping other conditions unchanged, 0.7 mmol of dipotassium ethylenediaminetetraacetate was added to solution B.

[0084] Please see Figure 8 The figure shows the charge-discharge curves of the iron-based Prussian blue cathode material prepared in Comparative Example 1 for an aqueous zinc battery.

[0085] Comparative Example 2

[0086] Based on Example 2, keeping other conditions unchanged, 0.7 mmol of dipotassium ethylenediaminetetraacetate was added to solution B.

[0087] Please see Figure 9 The figure shows the charge-discharge curves of the manganese-based Prussian blue cathode material prepared in Comparative Example 2 for an aqueous zinc battery.

[0088] Please see Figure 10 The figure shows the charge-discharge curves of the aqueous zinc battery cathode iron-based Prussian blue materials prepared in Examples 1, 3, and Comparative Example 1. By comparing the aqueous zinc battery cathode iron-based Prussian blue materials prepared in Examples 1, 3, and Comparative Example 1, it can be seen that the aqueous zinc battery cathode iron-manganese Prussian blue material prepared under the conditions of Example 3 has the best electrochemical performance at 0.5 A g. -1 At a current density of 104 mAh g, its specific capacity can reach 104 mAh g. -1 Because iron-based Prussian blue itself does not fully utilize the Fe(III) / Fe(II) redox sites, only a portion of Fe participates in the redox process, making it difficult to increase the capacity of iron-based Prussian blue. Please refer to [link to relevant documentation]. Figure 11 The figure shows the charge-discharge curves of the manganese-based Prussian blue cathode materials prepared in Examples 2-3 and Comparative Example 2 for aqueous zinc batteries. By comparing the manganese-based Prussian blue cathode materials prepared in Examples 2 and 3 with those prepared in Comparative Example 2, it can be seen that the iron-manganese Prussian blue cathode material prepared in Example 3 has the best electrochemical performance at 0.5 Ag. -1 At a current density of 104 mAh g, its specific capacity can reach 104 mAh g. -1 Because manganese-based Prussian blue is prone to Jahn-Teller distortion during phase transitions, leading to significant structural deformation of the MnN6 octahedron, the use of the strong coordinating agent dipotassium ethylenediaminetetraacetate not only slows down the Mn... 2+ The release rate is improved while manganese vacancies are introduced onto the material surface. These manganese vacancies can suppress the movement of Mn-N bonds and reduce the Jahn-Teller distortion of the MnN6 octahedron, thus significantly improving electrochemical performance. Battery performance test results show that the aqueous zinc battery cathode iron-manganese Prussian blue material provided by this invention has excellent electrochemical performance. By constructing a structure with two coexisting coordination states, the crystal structure is stabilized, and the dissolution of active atoms during cycling is suppressed. By adjusting the concentration of dipotassium ethylenediaminetetraacetate, the content of manganese vacancies is controlled, effectively suppressing Jahn-Teller distortion, preventing structural damage to the iron-manganese Prussian blue, and achieving a long cycle life. Based on these characteristics, this aqueous zinc battery cathode iron-manganese Prussian blue material has the advantages of high specific capacity, long cycle life, and good rate performance.

Claims

1. An application of an iron-manganese Prussian blue cathode material, characterized in that: The iron-manganese Prussian blue cathode material is used in aqueous zinc batteries; The preparation method of the iron-manganese Prussian blue cathode material includes the following steps: (1) Solution preparation: Dissolve K4Fe(CN)6·3H2O in deionized water to obtain solution A, and dissolve FeSO4·7H2O, MnSO4·H2O and the complexing agent in deionized water to obtain solution B; The concentration of K4Fe(CN)6 in solution A is 0.02 mol / L. -1 ~ 0.06 mol L -1 The concentration of FeSO4 in solution B is 0.008 mol / L. -1 ~ 0.04 mol L -1 The concentration of MnSO4 is 0.02 mol L. -1 ~ 0.04 mol L -1 The concentration of the ligand is 0.008 mol L. -1 ~ 0.3 mol L -1 ; (2) Coprecipitation synthesis: Solution B is added to solution A at a certain rate, stirred and mixed, aged, and the precipitate is separated by centrifugation, washed with ethanol and deionized water, and dried in a vacuum oven at 70-90°C to obtain iron-manganese Prussian blue cathode material; In step (1), the ligand is selected from either dipotassium ethylenediaminetetraacetate or tripotassium citrate.

2. The application according to claim 1, characterized in that, In step (2), the addition rate of solution B is 6 mL / min. -1 ~ 12 mL min -1 .

3. The application according to claim 1, characterized in that, The reaction temperature in step (2) is 5°C ~ 60°C.

4. An aqueous zinc battery, characterized in that: The aqueous zinc battery contains an iron-manganese Prussian blue cathode material, which is prepared by any one of the preparation methods described in claims 1-3.

5. The aqueous zinc battery according to claim 4, characterized in that: The method for preparing the positive electrode of an aqueous zinc battery is as follows: Iron-manganese Prussian blue cathode material, acetylene black, and polyvinylidene fluoride are ground in a mortar, N-methylpyrrolidone is added, and then ground again to obtain a slurry. The slurry is uniformly coated on the surface of the current collector and then vacuum dried to obtain a loaded cathode sheet. The mass ratio of the iron-manganese Prussian blue cathode material, acetylene black, and polyvinylidene fluoride is (6-8):2:

1.

6. The aqueous zinc battery according to claim 5, characterized in that: The battery assembly is as follows: Under room temperature conditions, the positive electrode shell, the loaded positive electrode sheet, the separator, the electrolyte, the negative electrode sheet, the gasket, the spring sheet, and the negative electrode shell are stacked in sequence and sealed with a sealing machine. An aqueous solution containing zinc trifluoromethanesulfonate is used as the electrolyte to complete the battery assembly.

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